1. Field of the Invention
The present invention relates to a jigsaw type electric-power cutting machine having a blade holding mechanism.
2. Background Art
A conventional electric-powered cutting machine will be described with reference to FIGS. 1 and 18, taking a jigsaw as an example.
As shown in FIG. 1, a jigsaw includes: a housing 2 which has a switch 4 and a handle 3, in which a base 5 that serves as a guiding member during a cutting operation is attached to a lower side, and which houses an electric motor 100 as is known in the art and that is schematically shown in FIG. 1; and a plunger 1 which reciprocates in the vertical directions in the figure by a turning force of the electric motor 100. In the illustrated jigsaw, the plunger 1 is covered by a cover 6 which is formed by a transparent member. An upper portion of the plunger 1 is reciprocatively held inside the housing 2, and a lower portion protrudes to the outside from the housing 2. A blade 7 is detachably held by the lower portion of the plunger 1.
As shown in FIG. 18, the conventional jigsaw has a configuration in which a locking screw 28 that presses against a flat face of the blade 7, and a support member 29 that supports a flat face of the blade 7 on the side opposite in the pressing direction are attached to the tip end of the plunger 1. When the blade 7 is inserted into the plunger 1, the blade 7 can be fixed to the plunger 1 by fastening the locking screw 28.
However, the above-mentioned configuration has the inconvenience that it is necessary to use a tool for operating the locking screw 28 during a work of replacing the blade 7. Apparently, the fastening force acting on the locking screw 28 is variously changed depending on the worker, thereby causing a problem in that, when the fastening force is excessively large, the blade 7 is deformed.
As a jigsaw for solving the problem, European Patent Nos. 722,802 and 855,239 disclose a configuration in which a work of replacing a blade can be conducted without using a tool or the like.